In the prior art, the chemical occult blood test or the immunological occult blood test are known as the methods for simply and easily detecting abnormalities in the digestive tract such as the stomach or intestine. According to these methods, stool samples are taken from subjects, and sensitivity of the reagent is adapted to the anticipated amount of stool. The sample must be in the precise amount to achieve the best result; if it is too little or too much, the reagent does not react and the amount must be adjusted. As the sample contains solids, unpleasant odors and extra disposal steps are necessarily involved.
As such prior tests require the subject to collect his/her own stool, there have been developed various tools for this purpose.
For example, Japanese UM application laid open as Sho 62-69160 discloses a sampling stick at one end of which is formed a throughhole and the like in the direction perpendicular to the axis of the stick. As the end of the sampling stick is thrust into the stool sample, a small amount of stool adheres in and around the hole. This sampler is defective in that its shape is unsuitable for collecting watery stool samples; it essentially requires a filter for filtrating the solid content; it requires dexterity on the part of the subject in collecting just the precise amount of sample in order to prevent errors in judging results; and it inconveniently involves extra steps of suspending the sample in physiological saline and filtrating the same, thus imposing much burden on the subjects and those conducting the test.
Japanese Patent Application laid open as Sho 59-182367, on the other hand, discloses a diagnostic tool consisting of a carrier for absorbing/adsorbing monoclonal antibody specific to human hemoglobin on the surface of a dip stick in order to detect trace blood in the stool samples. This diagnostic tool requires an additional step in manufacture for absorption/adsorption of monoclonal antibody at the end of the dip stick. There is always a doubt about whether or not the carrier sufficiently absorbed/adsorbed monoclonal antibody. In addition, the cited art requires extra steps of filling the stool sample inside the cavity formed at the tip of the carrier and of washing the sample away with water, thus proving complex and inconvenient.
Japanese Patent Application laid open as Sho 61-228351 discloses a sampling spoon provided with latticed notches on the surface of a polymer material (particularly hydrophobic plastic resin). After the stool is collected and attached to the surface of the sampling spoon, the spoon is left standing for a prescribed period of time in a buffered solution adjusted to interfere with the activities of digestive enzymes in the stool and to adsorb hemoglobin on the spoon surface.
As the sampling spoon used in this method is made of a hydrophobic plastic material, it cannot be used for sampling all types of stools, especially watery ones. At the same time, solid stool caught in the latticed grooves must be completely discharged into the buffer solution in order to carry out the subsequent processes smoothly.
The present inventors assiduously worked in order to offer a hemoglobin sampler which obviates these problems of conventional samplers and which can be used to sample hemoglobin alone from any forms or types of stools simply, easily and in precise quantities without unpleasant odors and in a clean manner. The inventors have come up with an idea of sampling hemoglobin alone by using the capillary action, and conducted experiments. As a result of such experiments, the inventors have learned that the material and shape of a hemoglobin sampler affect the success in sampling.
U.S. Pat. No. 4,789,639 discloses the method of immersing the absorbent pad of a swab in the liquid in a container and then collecting only the minimum amount of liquid by pulling the pad through a hole of a size substantially the same as the pad. The pad is made of a cotton swab and comprises a shaft attached with a relatively soft mass of randomly entangled fibers, the mass being larger than the shaft diameter at the end thereof. The device, however, is inconvenient as an increasingly large force is required to squeeze out the sampled liquid corresponding to the decrease in the liquid amount.
The sampling process consists of immersing and squeezing the sample. This means that sampling solid or relatively soft stools is quite difficult. A large amount of undigested solids in the stool attach to the enlarged portion of the absorbent pad or between the fibers, thus interfering with the effective sampling of hemoglobin in the stool.
U.S. Pat. No. 4,334,879 discloses an applicator for uniformly applying with pressure the liquid sample in a fine straight line on the cellulose acetate film, the applicator tip being made of a liquid absorbing porous body such as foam plastic, foam rubber or ceramics. This applicator is used only for sampling the liquid and for uniformly applying the liquid sample in a straight line on a prescribed surface. It is not suitable for sampling hemoglobin out of the stool samples. The applicator has an applicator blade made of a porous material which is immersed in the liquid sample, and then pressed under pressure onto the support to apply the sample. If the porous body does not become deformed by the pressing operation, uniform application cannot be made as the liquid does not seep out of the pores of the porous body onto the support. Thus, a hard material such as ceramics is not suitable for application under pressure.
Use of fine sintering particles generally provides a smooth surface but not continuous pores in the ceramics. If gross particles are used to form continuous pores, the texture becomes brittle and the surface rough. The former cannot quite absorb the liquid, and therefore notches must be cut as in the above mentioned conventional samplers. In the latter, a number of small pores are formed in the ceramic by the irregular surface of sintered particles, thus lacking directivity for the capillary action and delaying the absorbing rate of the liquid.
Foam plastics and rubber are made up of numerous cells which generally have large diameters and extremely thin cell membranes compared to their diameter. Thus, they lack directivity for the capillary action, and have weak absorbing force although it can be impregnated with or maintain the liquid.
These porous bodies are, therefore, not useful for sampling soft watery stools or hard stools with little water content, because they tend to absorb undigested solids rather than the water in stool.
The present invention was completed as a result of a series of studies to obviate the above mentioned problems. It offers a hemoglobin sampler for sampling and collecting the liquid content alone from hard stools containing a relatively small amount of water, soft stools containing relatively large amounts of water, or watery stools, and trapping occult hemoglobin in the stool while preventing the solid content from mixing into the sample.